Ok, Finally got the link to come up. I do like the idea, however, my only concern, as it was stated in the thread, is if the wing would collapse under vacuum pressure when you are sheeting it.

Also, I finally got around to buying the registered copy of Profili so I could mess around with the foam core wing settings. With this method, I would be able to do full length lightening holes, or tunnels, with a basic hot wire setup that I have... No need for a 3-axis cnc (but dont tell my wife, as I still want to build one eventually).

With this method, the wing is split along the center line of the profile, so there is an upper half and a lower half. While at first I was not crazy about this idea, it does allow for the use of a second set of templates that are then used to cut the holes. It will also add the template for the spars, however, just messing around with this on my own with some other template I already had, this is not the best method for such a narrow slot.

I might have to try both methods to see which will produce the better finished product. Maybe do a 24" panel as a trial run for both.

I have built several foam winged airplanes that turn out lighter than others builds that are all balsa. I am very picky about wood selection. I rarely use the supplied wood when I do build a all wood kit. In that case, I copy all parts and build my own kit. Now if built by the same person, an all balsa wing should be lighter than a foam/ balsa sheeted wing. Just food for thought.

Plane tech, if you're planning on bagging the wings, then no, you don't want to honeycomb them, as you need a consistent substrate.

Sorry, it got a bit confusing, I'm talking in three directions at once, lets go through it peicemeal.

1. a honeycombed balsa sheeted wing. In this instance you have a light core (1lb foam) that's honeycombed, and then sheeted with balsa. It's a good way of getting a light wing, but in the instance of an electric sailplane it's probably not the best, as you have a lot of span but not much chord, so what gains you make in honeycombing you'll lose in making it strong enough. Works well for lower aspect ratio wings though.

2. Bagged wing. well this is a known entity, and there's lots of info about it in the composites fabrication area. The issues are hinging control surfaces and hiding servos. It's really if you're chasing that last percent of awesome out of the wing.

3. built up sheeted or partially sheeted wing. This is not a bad way to go if, like you say you have the time. I'd look up Jack Womack's (Schrederman) Houston Hawk for details on a really good built up sailplane wing in the thermal forums. Jack's a master at building the lightest, strongest woody wings.

1. a honeycombed balsa sheeted wing. In this instance you have a light core (1lb foam) that's honeycombed, and then sheeted with balsa. It's a good way of getting a light wing, but in the instance of an electric sailplane it's probably not the best, as you have a lot of span but not much chord, so what gains you make in honeycombing you'll lose in making it strong enough. Works well for lower aspect ratio wings though.

That makes sense.

So, we are back to the two original options... standard fare foam core bagged wings or built up...

Quote:

Originally Posted by Curare

2. Bagged wing. well this is a known entity, and there's lots of info about it in the composites fabrication area. The issues are hinging control surfaces and hiding servos. It's really if you're chasing that last percent of awesome out of the wing.

The hinging and servo hiding is a problem no matter what style of wing you build as far as I am concerned. Servos only get so small and have enough torque to drive the control surfaces of a plane of this size... without taking out a second mortgage that is...

Quote:

Originally Posted by Curare

3. built up sheeted or partially sheeted wing. This is not a bad way to go if, like you say you have the time. I'd look up Jack Womack's (Schrederman) Houston Hawk for details on a really good built up sailplane wing in the thermal forums. Jack's a master at building the lightest, strongest woody wings.

I looked up and read into a couple of Schrederman's builds, the Houston Hawk and the Yardbird. Both had some very excellent examples of why I like to do a built up wing. It just looks better when its done. I also got a couple good ideas as far as spar structure goes

So, I really an back to the beginning again...

Now I am looking at a compromise of sorts, but I am not sure of any benefits that would be gained.
My thought is to make the center panel, which is the constant chord section, and where the most strength is needed to support the outer panels and the boom mounts, built up, and sheeted, and the outer panels will be foam. Does that even make sense to do? Maybe I am just thinking about it too much...

If I remember correctly the old Legionaire wing was built the other way around, foam core centre section (with some serious reinforcement ) and built up tips, to keep the moment of inertia to a minimum, at least that'd be why I'd do it.

At the end of the day, I don't think either way will be the wrong way, you may as well pick the one that's most appealing

At the same time I've seen no mention of location. If you live in mountains or hills a heavy foam core wing would work better and a flat lander would find a built up lighter and better for soaring. On the other hand I find built up easier and faster for prototyping and testing and foam core is just better when done right!